Microbiology Refresher - Bacteria Flashcards
Lobar bacteria is most likely what type of infection?
bacterial infection
What are the 3 questions to ask when identifying causative bacteria?
- what is the source of infection?
- which pathogenic organism(s) could be responsible?
- what do I know about the possible gram status of the responsible organism?
What type of cell has a cytoplasm, a nucleoid, but no membrane enclosed in a nucleus?
prokaryote (bacteria cell)
What contains a single-stranded DNA for reproductive purposes and a circular plasmid DNA?
prokaryote
There is enough difference between (1) of humans and bacteria that some antibiotics will impair function of (2) without killing the (3)
- ribosomes
- ribosomes
- host
What helps with locomotion is prokaryotes but is not present in all bacteria?
flagellum
What allows bacteria to adhere to surfaces such as teeth?
pili
What resides in the human microbiota and one or both organisms may benefit from this relationship?
commensal microorganism
If both human and commensal microorganism benefit in the relationship, what is it termed?
mutualistic relationship
What is a microorganism that is not typically a part of the human microbiota that may or may not not disease?
non-commensal microorganism
What can be commensal or non-commensal organisms that cause disease?
pathogen
What are the 4 different types of pathogen?
- obligate pathogen
- commensal pathogen
- zoonotic pathogen
- environmental pathogen
What type of pathogen needs to be transmitted to survive?
obligate pathogen
What type of pathogen may be part of the microbiota but can also cause regular disease and does not require presence of disease to survive?
commensal pathogen
What type of pathogen is transmitted to human from animals directly (animal products via an insect vector), and does not require presence of disease to survive?
zoonotic pathogen
What type of pathogen includes a pathogenic microorganism that is acquired through exposure in the environment, such as water or soil, and does not require the presence of disease to survive?
environmental pathogen
What type(s) of pathogen(s) do not need the presence of disease to survive?
- commensal pathogen
- zoonotic pathogen
- environmental pathogen
What type of pathogen is Mycobacterium tuberculosis and why?
obligate pathogen
needs to be transmitted to others, typically through coughing, to survive
What type of pathogen is Staphylococcus aureus and why?
commensal pathogen
exists on skin, but can sometimes cause abscesses of the skin & does not require the presence of the abscess to exist or survive
What type of pathogen is Yersinia pestis and why?
zoonotic pathogen
was carried by fleas carried on rats that travelled throughout Europe and Asia, causing a plague pathogen
What type of pathogen is Legionella pneumophila and why?
environmental pathogen
resides in hot tubs and building water systems - does not require disease to survive
Describe obligate aerobes?
requires oxygen for growth
Describe obligate anaerobes?
cannot grow in presence of oxygen
Describe facultative anaerobes (aerobes)?
prefers oxygen for growth, but can grow in its absence
Describe aerotolerant anaerobes?
does not use oxygen to grow, but can tolerate it
Describe microaerophiles?
prefers reduced amounts of oxygen to grow
What type of infections can occur when bacteria are displaced from their natural body habitat - endogenous acquisition?
anaerobic infections
What type of infections can occur when a barrier is broken such as in trauma, infection, or tumor?
anaerobic infections
Oxygen may be excluded from the area is which cases?
- obstruction
- surgery
- trauma with tissue damage
What loves dead tissue (non-oxygenated) and are happy to grow in damaged tissue?
anaerobes
If there are aerobes or facultative bacteria present simultaneously with anaerobes, anaerobes can further reduce oxygen level in affected area, resulting in (1)
- more anaerobic growth
What can also be acquired exogenously (outside the organism, such as soil)?
anaerobes
What are these symptoms of:
- putrid odor coming from wound/region
- tissue necrosis or gangrene (black discoloration)
- gas present in area of infection
- skin trauma where normal flora exists but skin barrier is broken (fights, bites, trauma, recent surgical incision)
- patient not improving & initial antibiotics had no coverage for this organism
anaerobic infection
What type of organisms tend to be more responsive to antibiotics?
gram-positive organisms
What has a thick peptidoglycan layer that acts as an easy target for antibiotics and allows for antibiotics to absorb well into it?
gram- positive organisms
What type of membrane do gram-positive organisms have?
phospholipid bilayer
What is a good example of medication that has typically been used against G+ organisms because it prevents cross-linking of peptidoglycan chains?
penicillin
Unlike gram-positive organisms, gram-negative bacteria have what type of cell walls?
thin cell walls
What are the cell walls of gram-negative bacteria composed of?
outer membrane (OM) of lipopolysaccharides (LPS) with porin channels connected to layer of peptidoglycan
What is a very selective barrier in gram-negative bacteria due to its lipid bilayer?
outer membrane (OM)
Because gram-negative bacteria have a selective outer membrane, what happens to antibiotics?
some antibiotics are blocked, so there will be no affect
What does this describe in gram-negative bacteria?
- allows diffusion of certain molecules based on size
- can block out some, but not all, antibiotics
- involved in inflammatory mediator release
porin channels
A large percentage of bacteria that develop resistance are (1)
- gram-negative bacteria
Changes in (1) of gram-negative bacteria are key in resistance
- liposaccharide outer membrane
What type of bacteria changes so frequently that treatment changes often as well?
gonorrhea
What is a gram-negative bacterium that causes cervicitis in women or urethritis in men; patients can be asymptomatic or present with discharge, pelvic pain, and systemic symptoms like fever; and is becoming harder to treat?
Neisseria gonorrhoeae
Most gut bacteria is (1)
- gram-negative
These organisms are what type of gram:
- staphylococcus
- streptococcus
- enterococcus
- peptostreptococcus
gram-positive
Enterobacteriaceae are gut bacteria that are (1)
gram-negative
What gram stain is staphylococcus?
gram-positive
What gram stain is streptococcus?
gram-positive
What gram stain is corynebacterium?
gram-positive
What gram stain is mycobacterium?
gram-positive
What gram stain is bacillus?
gram-positive
What gram stain is clostridium?
gram-positive
What are some other pathogenic features of bacteria?
- toxins produced can have devastating effects (toxic-shock syndrome)
- capsule or “slime layers”
- spores/endospores
What makes bacteria “slippery” and can be able to evade phagocytosis?
capsule or “slime layers”
Where are spores primarily found in?
gram-positive bacteria
What allows bacteria to be dormant and resistant to harsh conditions?
spores
You may have to increase effort to kill when (1) are present?
spores
What is defined as a collection of bacteria composed of 10 million to 10 billion cells per gram of dehydrated material?
biofilms
Biofilms are covered in a matrix that the bacteria assembles as a way of:
attachment/adhesion
- on surface of teeth
protection
- “like-minded
- can withstand some antibitiocs
detachment
- if colony is weakened, it can detach and propagate elsewhere
What are characteristics of atypical bacteria?
- lack cell wall
- not visible when gram-stained
- not easy to culture organism
What are these examples of?
- Mycoplasma
- Chlamydia
- Legionella
atypical bacteria
What are treatable with antibiotics, such as macrolides and tetracyclines?
atypical bacteria
What are big differences in skin colonization even between healthy individuals attributed to?
- age
- sex
- immune system
- genotype
- hygiene
- occupation
- environment
- underlying diseases
What occur in various areas of the body covered by skin?
bacterial niches
What are abundant in moist/humid areas, such as feet and antecubital fossa?
staphylococcus
A lot of skin bacteria are what type of stain?
gram-positive
Is staphylococcus aerobic, FA, or anaerobic?
facultative anaerobe
Is streptococcus aerobic, FA, or anaerobic?
facultative anaerobe or anaerobe
What describes when the microbiota is not doing the correct thing?
dysbiosis
What is propionibacterium acnes associated with?
acne
What is another name for atopic dermatitis?
eczema
What appears to flare when there are increased quantities of Staphylococcus epidermidis and Staph aureus (but not sole cause)?
eczema (atopic dermatitis)
What locations on the body does eczema favor?
- inside of elbow
- location varies with age
The human has (1) types of bacteria in the mouth
many (70 different genera)
What type of bacteria resides in the human mouth?
both gram positive and negative
The oral cavity is dominated by abundant (1) species of many kinds
streptococcus gram positive bacteria
Streptococcus species in the oral cavity have what type of function?
- help metabolize carbohydrates
- some can inhibit growth or more virulent, disease-causing strains
What looks just like strep throat?
mono
What part of the gut has transient bacteria from the mouth or stomach?
proximal esophagus
What part of the gut is dominated by gram-positives (mostly streptococcus species) and also includes gram-negatives?
distal esophagus and stomach
What part of the gut includes both gram positives (streptococcus and clostridium) and gram negatives (E. coli)?
small and large intestine
What can change your microbiota for 6-12 months?
antibiotics
What is located anterior nares to the larynx?
upper respiratory tract
What is located from the larynx to alveoli?
lower respiratory tract
Staphylococcus, streptococcus, and corynebacterium species can all be found where?
upper and lower respiratory tract
The main source of microbes for the lungs appears to be the (1) in adults and the (2) and (3) in children?
- oropharynx
- nasopharynx
- oropharynx
Which respiratory tract has more organisms?
upper respiratory tract
What is found in the nares of 1/3 of the population and what can this result in?
staphylococcus aureus
- can result in infection of the bloodstream (sepsis) or skin around an infection
The vaginal microbiota is predominantly what species?
Lactobacillus species
What helps maintain healthy vaginal pH (<4.5) through the byproduct of lactic acid?
lactobacillus species
What type of stain in lactobacillus?
gram-positive
Is lactobacillus aerobic, FA, or anaerobic?
anaerobic
What can having an adequate amount of lactobacillus protect against?
- overgrowth of other anaerobes and the symptomatic infections that result
What are some ways to diagnose a bacterial infection?
- rely on history and physical findings (80% of time, you’ll know what’s wrong)
- in some cases, blood tests (CBC and other inflammatory mediators elevated)
- sometimes we can send fluid out for analysis, culture and sensitivity (can take 24-48 hours to get results)
What are some cultures we can use for bacterial infection analysis?
- urine
- sputum
- blood
- stool
- pus
- CSF or joint fluid
What are different tests for susceptibility testing of bacterial infections?
- agar dilution test
- disk diffusion test
What type of test does this describe:
antibiotic is mixed with agar and bacteria are plated on antibiotic specific agar (one plate can test 32-36 bacteria )
- results are read at lowest concentration of antibiotic that inhibits growth
agar dilution test
What type of test does this describe:
bacteria is swabbed on agar plate, then filter discs are placed on top; after incubation, area around disks are measures (simple, reliable, and used frequently)?
disk diffusion test
What is the result obtained on susceptibility tests?
minimum inhibitory concentration (MIC)
What gives the lowest concentration of antibiotic that inhibits growth of that bacteria?
minimum inhibitory concentration (MIC)
What are the results you can get from MIC?
- S=susceptible
- I=intermediate
- R=resistant
What can be performed on a patient presenting with prolonged diarrhea?
stool cultures
What bacteria are true pathogens and if found in blood cultures, could mean patient is septic?
- staphylococcus aureus
- streptococcus pneumoniae
- escherichia coli
- pseudomonas aeruginosa
- klebsiella pneumoniae
- candida albicans
